Add background image to all APEX pages

background-image.css

/*Assumes APEX 5 + Universal Theme*/
.t-Body-content{
  background-image: linear-gradient(#e66465, #9198e5);
                  /* 
                  Instead of generating a gradient, it is possible to point to a specific file
                  url("path/to/my/image.svg")
                  
                  */
}